That is indeed a very odd thing to see, are you certain it was there all this time ?
I would imagine it would take an almighty smack or intense mistreatment to cause it.
My thought is it may have been poorly placed into a case opener, too loosly clamped & then slipped under tension.

I have only owned one Camaro ( a 9220 )

and mine did not have the springbar holes go all the way through the lugs.
Yours is the first Camaro i have seen with lug holes drilled all the way through, could this also have something to do with the matter ????
- Darren

: I have an otherwise lovely Camaro 7743 (noir) that I recently
: noticed has developed a crack in the back of the case, on the
: pusher side.

: Not sure what could have caused this... over-torqueing the back
: perhaps, metal fatigue, defect in the original case?

: I've handled quite a few of these but haven't run across this
: before.

: I suppose I'll be looking at repair or replace options!

: Any member advice would be welcomed.